Field of the Invention
The present invention relates to a pneumatic tire including a rib pattern on a tread surface.
Description of the Related Art
A tread surface of a pneumatic tire is provided with a plurality of main grooves continuously extending in a tire circumferential direction, and land parts such as ribs or blocks, which are divided by the main grooves, to form various tread patterns depending on required tire performance and use conditions. Because the rib has higher stiffness than the block, to enhance irregular wear resistance, a rib pattern is superior to a block pattern. However, the rib pattern tends to have lower traction performance and skid resistance than the block pattern.
Patent Documents 1, 2 disclose a pneumatic tire employing the rib pattern, but fail to suggest a means for counteracting a decrease in skid resistance in the rib pattern. Further, Patent Documents 3, 4 also disclose a pneumatic tire employing the rib pattern. However, a rib provided at the center in the tire width direction has relatively high ground pressure and thus, can be greatly deformed. Accordingly, there is a room for improvement of irregular wear resistance.